Known devices for controlling gas-burner rings of a cooking surface (both of the type which can be installed built-in and of the type forming part of a combined electrical household appliance, including, for example, an oven and/or a dish-washer) comprise for each gas-burner ring a gas tap and a catenary element provided with microswitch, actuation of which energizes a service gas-lighter circuit of the cooking surface, of a known type, which produces a spark on one or all of the gas-burner rings. In general, the gas tap is provided with an axially mobile and rotatable element, equipped with a control knob, rotation of which (possible, for safety reasons, only by a simultaneous axial translation of the mobile element) enables supply of the combustible gas to the gas-burner ring.
In order to guarantee ignition of the combustible gas as this is supplied to the gas-burner ring, the axial movement of the mobile element/control knob is used also to actuate the microswitch, thus producing generation of the ignition spark simultaneously with supply of gas.
In known devices the microswitch is actuated either via a contrast element carried by the mobile element of the gas tap, a contrast element which in general consists of a snap ring or else a bushing fixed on the mobile element of the gas tap via a snap ring, or else via a contrast shoulder made directly on the control knob.
The solutions of the first type, however, can be applied only in the presence of catenaries with spring actuation (which are more costly than the springless ones), in so far as, in order to enable installation of the bushing and/or of the snap ring, both must present a sufficiently extensive radial discontinuity in the angular direction so as to enable its deformation to fix it via snap action. Said discontinuity, in fact, in the absence of a spring, would not guarantee actuation of the microswitch in any angular position for installation of the bushing/snap ring.
The solution of the second type, which uses the control knob as contrast member, is costly and inconvenient, in so far as it does not enable use of catenaries of a standard type, but it is necessary to provide catenaries specifically tailored for each type of cooking surface.